This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 10-339333, filed Nov. 30, 1998; and No. 10-339334, filed Nov. 30, 1998, the entire contents of both of which are incorporated herein by reference.
The present invention relates to an apparatus for measuring the height, position and the like of an object.
In recent years, the integration densities and scales of semiconductor components are ever increasing. Among the semiconductor components are electrical-part packages, such as BGA packages each having electrical components such as bare chips. One type of a BGA package includes bare chips with bumps formed by FC bonding. It is demanded that the position, height and the like of each element incorporated in such a BGA package be measured more accurately than before.
Hitherto, inspectors examine electrical components each having bumps. More precisely, they examine the components one by one, by using microscopes, for the positions and heights of the components.
It takes them much time to examine the outer appearance of each electrical component, however. The efficiency of the examination is inevitably low. Additionally, the examination is cumbersome, which annoy the inspectors greatly.
To acquire high-quality images of samples, it is necessary to adjust the light from the laser diode (i.e., light source) to an optimal intensity.
Some methods have been employed to control the intensity of the laser beam emitted from the laser diode. One method is to change the power-supply voltage applied to the laser diode, thereby to control the intensity of the laser beam. Another method is to arrange in front of the laser diode an ND filter whose transmittance gradually varies and move the ND filter, thereby to control the intensity of the laser beam.
If the power-supply voltage of the laser diode is changed, however, the laser beam will have an unstable wavelength. It will be then difficult to acquire high-quality images. If an ND filter is used, the laser beam cannot have uniform intensity after it has passed through the ND filter. This is because points on a specified cross section of the laser beam that has passed through the ND filter tend to exhibit different intensities.
Another method may be available to control the intensity of a laser beam is available. A polarizing plate is arranged in the path of the laser beam and rotated, thereby to change the intensity of the beam as the beam passes through the plate. However, optimal brightness varies in accordance with the position and condition of measuring the sample. Consequently, it is difficult to acquire a high-quality image at all times.
Accordingly, it is an object of the present invention to provide a measuring apparatus that can perform various measuring processes at high accuracy and within a short time, thereby much relieving inspectors.
It is another object of the present invention to provide a measuring apparatus that can always acquire an image of a sample, which has optimal brightness, even if the position and condition of measuring the sample change.
According to an aspect of the invention, there is provided a measuring apparatus comprising: first measuring means including a measuring light source for emitting a measuring light, an objective lens, provided to oppose a sample, for focusing the measuring light on the sample, scanning means for two-dimensionally scanning a surface of the sample with the measuring light passing through the objective lens, an optical system for guiding a light beam reflected by the sample to a plane on which a pupil of the objective lens is projected and focusing part of the guided light beam, the part of the guided light beam to be focused having an optical axis positioned apart for a distance from that of the guided light beam, optical position detecting means, provided on a plane where the part of the guided light beam is focused by the optical system, for detecting a shift amount of a beam-spot that shifts in accordance with a height of the sample, and height-calculating means for calculating the height of the sample from the shift amount detected by the optical position-detecting means; and second measuring means for receiving through the objective lens a light reflected from or scattered by the sample to which an illumination light is applied from an illumination light source, and thereby acquiring two-dimensional data, wherein the objective lens is provided on a position where an optical axis related to the first measuring means and an optical axis related to the second measuring means overlap each other.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.